Earth moving apparatus with vibrating cutting edge



EARTH MOVING APPARATUS WITH VIBRATING CUTTING EDGE Filed 001;. 18, 1967 Nov. 18, 1969 E. R. CUNNINGHAM 4 Sheets-Sheet 1 INVENTOR. E rnesf R. Cunningham His An'y Nov. 18, 1969 E. R. CUNNINGHAM 3,478,450

EARTH MOVING APPARATUS WITH VIBRATING CUTTING EDGE Filed 001;. 18, 1967 4 Sheets-Sheet 2 E -12 INVENTOR.

Ernest R. Gunning/mm Nov. 18, 1969 E. R. C'UNNINGHAM 3,478,450

EARTH MOVING APPARATUS WITH VIBRATING CUTTING EDGE Filed Oct. 18, 1967 4 Sheets-Sheet 5 1-7 19 H1 15 H 217 ff m r 1' M r INVENTOR. Ernest R. Cunnmgham His AH'y Nov. 18, 1969- E. R. CUNNINGHAM 3,473,450

EARTH MOVING APPARATUS WITH VIBRATING CUTTING EDGE 4 Sheets-Sheet 4 Filed Oct. 18, 1967 Fig: 23

.y R Y O: om m m 5 0. i E n H V 5% 1 u United States Patent 3,478,450 EARTH MOVING APPARATUS WITH VIBRATING CUTTING EDGE Ernest R. Cunningham, Libertyville, Ill. (8501 W. Higgins Road, Chicago, Ill. 60631) Filed Oct. 18, 1967, Ser. No. 676,110 Int. Cl. E02f 3/ 76 US. Cl. 37-141 15 Claims ABSTRACT OF THE DISCLOSURE An earth moving shell for construction equipment having cutting blade means vibrated through a frequency range including a natural frequency, but limited in the amplitude of its vibratory excursions to obtain an efficient method of dislodging and moving compacted materials which are engaged by said cutting blade means.

Earth moving equipment, such as scrapers, motor'graders, bulldozers, end loaders, and the like, is customarily provided with a cutting element at the forward end of an earth loading bucket or shell which is designed to engage and remove a given volume of earth directly proportional to the depth of the cut. In many instances, the resistance offered to a cutting element by compacted or heavy soil materials is also proportional to the depth of cut and can exceed the maximum vehicle tractive force. When this occurs, the wheels or tracks, as the case may be, slip or spin and power is lost. Force is still being applied to the cutting element, but being of lesser magnitude than the resistive force there is no forward movement of the particular earth moving apparatus, and no useful work is performed. Energy is being converted to motion, but the work output is manifested through the spinning wheels or tracks, rather than through the cutting element. The operator of the particular earth moving apparatus is thus forced to reduce the depth of cut, thereby effecting a reduction in resistive force, restoring a positive balance of tractive force for cutting and loading the earth into the earth loading bucket or shell, and thereby avoid the difiiculty of spinning wheels or tracks. This results in a very relatively ineflicient method of dislodging earth even though it is the most commonly employed method of operation.

In an attempt to alleviate this problem, it has been the common practice in construction equipment design to increase vehicle weight and to increase the engine horsepower of earth moving equipment. This raises the maximum tractive effort level, but it also results in larger power train components, engines, transmissions, differentials, axles and larger tires or wider tracks to carry the additional load. In many large earth moving machines, the compromise required to achieve tractive effort which is needed for cutting and loading of earth has been at the expense of mobility and maneuverability. As a result, undesirable restrictions have been imposed on certain of these machines as to the types of soils upon which they may efficiently operate, and further the machines become more single purpose as they are rendered less adaptable to perform varying types of materials handling.

According to the present invention, only a portion of the prime power supply is converted to a form which may be applied directly to a cutting element for efficient dislodging of compacted materials so as to bypass the conventional power train and eliminate the inherent difiiculties of traction dependent systems. The direct application of power through a high level kinetic energy system, such as contemplated by the present invention, to a cutting element will result in high force levels which far exceed those which are possible through traction dependent systems. Further, controlled application of this power has the effect of reducing peak tractive effort demand, to obtain more of a constant balance between machine output and work load.

It is an object of the present invention to provide an earth moving apparatus which dislodges and moves all types of earth with greater speed and efliciency than prior art proposals.

Another object of the present invention is to provide an earth moving system the productive output capacity of which is dependent on the concentration of a high level kinetic force applied directly to the cutting element of an earth moving apparatus, instead of being dependent of tractive effort.

A further object of the present invention is to provide an earth moving apparatus wherein power is dissipated at the cutting element in intermittent fashion occuring only when resistance is ofiered to the cutting element by various types of earth.

Still further objects of the present invention are as follows: The earth engaging and moving components of the earth moving apparatus are very simple in construction and operation, such components are relatively inexpensive in comparison to the results which are achieved in its operation, such components can be embodied in many different and varied forms to suit various requirements, installation of such components of the earth moving apparatus are otherwise well adapted for the purposes intended.

These and other objects and advantages of the present invention are attained by providing, in an earth moving machine, thecombination of an earth moving shell having cutting blade means mounted thereon for movement relative to the earth moving shell, means for forced vibration of said cutting blade means through a frequency range including a natural frequency, and means for limiting the amplitude of vibratory excursions of said cutting blade means without affecting the impact force thereof when resistance is offered to said cutting blade means by compacted materials.

Reference is now made to the drawings wherein:

FIG. 1 is a side elevational view of a track laying-type tractor incorporating an earth moving shell at the forward end thereof constructed in accordance with the teachings of the present invention;

FIG. 2 is a top plan view of one form of earth moving shell and cutting blade assembly detached from the tractor as viewed along line 2-2 of FIG. 3;

FIG. 3 is a side elevational view of the earth moving shell and cutting blade assembly depicted in FIG. 2, and illustrating the manner in which the cutting blade assembly is mounted relative to the earth moving shell with the use of torsion bar suspension system and spring dampening components for its operation;

FIG. 4 is a fragmentary top plan view illustrating another form of earth moving shell and cutting blade assembly employing a pivotal linkage suspension connection between a torsion bar and a spring dampened cutting blade; FIG. 5 is a side elevational view similar to FIG. 3, but related to the form of invention depicted in FIG. 4;

FIG. 6 is a diagrammatic view illustrating the manner in which the cutting blade assembly is mounted for initial relative movement to the earth moving shell, and its predetermined maximum range of controlled movement which results from vibration dampening means employed in conjunction with the present invention;

FIG. 7 is a fragmentary top plan view illustrating an.- other form of earth moving shell and cutting blade assembly coming within the purview of the present invention;

FIG. 8 is a side elevational view showing a cantilever spring mounted cutting blade assembly through the use of a plurality of leaf springs and a compression spring system for dampening excursions of the cutting blade whichexceed the predetermined range of controlled movement;

FIG. 9 is a fragmentary top plan View similar to FIG. 7 illustrating the use of spirally wound compression springs in another form of the present invention;

FIG. 10 is a side elevational view of the form of the invention shown in FIG. 9;

FIG. 11 is a fragmentary top plan view of another form of earth moving shell and cutting blade assembly employing opposed, concentrically mounted spirally wound spring elements;

FIG. 12 is a side elevational view of the form of invention shown in FIG. 11;

FIG. 13 is a fragmentary top plan view showing yet another form of earth moving shell and cutting blade assembly utilizing the combination of opposed fluid motor means and spring means;

FIG. 14 is a side elevational view of the form of invention shown in FIG. 13;

FIG. 15 is a fragmentary top plan view depicting yet still another form of the present invention incorporating opposed, horizontally mounted compression springs which impose a force on the cutting blade generally at right angles to the path of the vehicle;

FIG. 16 is a side elevational view of the form of invention shown in FIG. 15

FIG. 17 is a fragmentary top plan view of yet another form of the present invention incorporating a vertically mounted torsion bar with oppositely acting spirally wound spring elements utilized in conjunction therewith, as best seen in FIG. 18, which gives a circular arc shearing action to each end of the cutting blade in its movement;

FIG. 18 is a side elevational view of the form of invention shown in FIG. 17;

FIG. 19 is a fragmentary top plan View of an earth moving shell and cutting blade assembly incorporating a resilient mounting system which operates in a different manner than the forms of invention shown in the other figures of the drawings;

FIG. 20 is a side elevational view of the form of invention shown in FIG. 19;

FIG. 21 is a side elevational View of earth moving equipment in the form of an end loader to which the present invention may also be adapted;

FIG. 22 is a side elevational view of the end loader bucket, and showing the manner in which the cutting blade assembly can be mounted relative thereto incorporating the principles of the forms of invention related to FIGS. 118; and

FIG. 23 is a front elevational view showing the end loader bucket from the open end thereof.

All land locomotion vehicles have a finite tractive force level, the upper absolute limit of which is the maximum engine horse power. The working range of most prime movers is reduced from this ideal force or upper absolute limit through transmission and power train losses of power. Thus, the tractive force level will be rated lower than the maximum engine horse power. There are certain vehicle systems, such as a crawler tractor, when so called full rated power is delivered to the wheels or tracks of the unit, but notwithstanding this, further loss in working power occurs due to a partial loss of traction with the earth. This loss in traction often expressed as percent slip, is further magnified when the cutting blade or edge of an earth moving shell attached to the forward end of the earth moving machine engages a resistive force, such as compacted materials or heavy soil materials, which approaches or exceeds the maximum tractive effort. When the latter occurs, there is no forward movement of the earth moving machine. The present invention is designed to relieve the total dependence of earth moving systems on the tractive eifort level of the particular earth moving apparatus, and rely upon the use of concentrated high level kinetic energy which is inherent and flows from the earth moving apparatus to which the present invention is directed.

Referring now to FIG. 1, there is shown a conventional track laying-type tractor 10 which is Supported on opposite sides by track elements 12 as is conventional, and which are each entrained about a driving sprocket 14 at the rear of the tractor and a forwardly positioned guide or idler wheel 16. An operators seat or area 18 is provided with various types of control levers and mechanisms for operating the tractor as is conventional. At the forward end of the tractor, there is provided an earth moving shell and cutting blade assembly 20 which includes a curved earth loading and moving shell 22 and a cutting blade assembly generally identified 24 in FIG. 1. The earth loading and moving shell 22 is mounted at the forward end of the tractor by means of horizontal main beam members 26 which extend on opposite sides of the tractor. The earth loading and moving shell 22 further is provided with laterally s aced lift cylinders 28 and lift arms 30 which are also connected to the main body of the tractor and which operate in a conventional manner.

Various types of earth moving shells and cutting blade assemblies, generally identified 20 in FIG. 1, are shown in the various figures of the drawings. As all but one of the embodiments of the present invention generally relates to the same principle of operation, similar reference numerals will be employed in the various forms of the invention illustrated in the drawings with corresponding sufiixes employed in alphabetical sequence to identify like or corresponding parts of the various earth moving shells and cutting blade assemblies shown.

Considering first the form of earth moving shell and cutting blade assembly shown in FIGS. 23, it will be seen that the overall earth moving shell and cutting blade as sembly has been identified 20a. As in the case with the other forms of invention shown in the drawings, the earth moving shell and cutting blade assembly 20a is shown in detached form from the tractor 10 so as to pinpoint the features of the present invention as distinguished from the conventional elements employed.

The earth moving shell and cutting blade assembly 20a includes an earth loading and moving shell 22a which is curvilinear in form to more readily accept and carry earth or other materials, and a cutting blade assembly 24a, the principal components of which will be presently discussed. The earth loading and moving shell 22a supports cutting blade assembly 24a at the upper end thereof by supporting plates 32 which are fixed or otherwise attached to journals 33 at opposite ends thereof. The earth loading and moving shell 22a, by reason of the manner in which it is afiixed to supporting plates 32 and the horizontal beam members 26 of the tractor, will remain in a relatively fixed and stable position.

The cutting blade assembly 24a includes a cutting blade 34 at the lower end thereof which is also mounted adja cent the lower end of the earth loading and moving shell 22a. The cutting blade 34 is mounted, at opposite ends thereof, to a pair of curvilinear rigid arms 36 which have a curvilinear shape generally similar to the earth loading and moving shell 22a. Each of the curvilinear rigid arms 36 have openings at the uppermost ends thereof to receive a torsion bar 38 which is suitable mounted in the bearing journals 33. The torsion bar 38 is rigidly afiixed generally at its midpoint to moving shell 22a such that it will permit twisting or circumferential movement proportional to applied torque. Since the torsion bar 38 is mounted at opposite ends in the bearing journals 33, the torsional movement will be applied through the rigid curvilinear arms from the cutting blade 34 for reasons which will appear hereinafter.

The cutting blade assembly 24a further includes a dampening spring system at the lower end thereof. In particular, this includes a pair of opposed springs 40, 42, each of which are mounted with free travel on opposite sides of a central spring platform 44. Dampening occurs when spring 40 is being compressed by outer spring platform 46 and spring platform 44 while the spring 42 is compressed between the central spring platform 44 and the inner spring platform 48 which is supported by the earth loading and moving shell 22a when cutting blade assembly 24a is moving the opposite direction. It will also be noted thateach outer spring platform 46 is supported through the use of supporting rods 50. Since the central spring platform 44 is attached to the cutting blade 34, the cutting blade 34 will have an initial relative movement (X) to the earth loading and moving shell 22a restrained only by the resilient torsion bar 38 suspension system. Thus, an initial-relative, but limited movement of the cutting blade 34 (shown as X in FIG. 6) with respect to the earth loading and moving shell 22a is provided. Additional movement (overtravel) of the cutting blade 23 is opposed by alternate compressive action of springs 40 and 42 having reached the limit of free travel.

To obtain a high level kinetic force in the cutting blade assembly 24a, an exciting device 52 is provided for applying predetermined amounts of unbalance force at a prescribed frequency in the desired excursion plane of the cutting blade. The exciting device 52 is attached in a centralized position on the cutting blade assembly 24a and may be of any type which functions in the manner described above. Specifically, the exciting device may comprise such mechanical exciting sources as a constant rotating eccentric mass, ball or roller type vibrators, a reciprocating air motor, a cam throw, an eccentric bearing or the like, such electrical exciting sources as an electromagnet, alternately energized electromagnets mounted in opposition on a magnetic portion of the cutter assembly or the like, or such fluid exciting sources or systems such as pneumatic and hydraulic systems. The exciting device 52 should also ideally incorporate means for variable frequency and adjustable force level controls.

The exciting source or device 52 is designed to apply an unbalanced force to the cutting blade assembly 24a to obtain a forced vibration of the cutting blade 34 through a frequency range including a natural frequency. To prevent unnecessarily large vibrations and to bring the vibratory effect which is created within the purview of the present invention, the cutting blade assembly 24a through its resilient torsion bar 38 suspension system and spring is designed to limit the maximum amplitude of the vibratory excursions of the cutting blade 34 without affecting its impact force within the working range of lesser amplitude when resistance is offered to the cutting blade such as by compacted materials or earth. Specifically, the torsion bar 38 has a limited amount of resilient free travel, and this together with the spring system provides inherent dampening of the excited cutting blade 34 which limit the maximum amplitude of excursion or control the vibrations thereof to the range of movement Y in FIG. 6, thereby preventing an infinite force build-up, and stabilizing the system to obtain maximum force reinforcement effect in the form of concentrated high level kinetic energy which can be utilized when resistance is offered to the cutting blade by compacted materials or earth.

Under the present arrangement, the cutting blade assembly 24a has a limited amount of initial free resilient movement relative to the earth moving and loading shell 22a, and this is depicted by the diagrammatic showing in FIG. 6, and specifically by the letter X which illustrates the amount of free relative movement of the cutting blade. One half of this free relative movement on each side of the fixed cutting blade 48 from a fixed or stable position of the cutting blade is denoted X/2. The range of movement (X/2) will be used throughout the various embodiments illustrated in the drawings to provide a ready reference symbol for understanding the operation of the present invention. The letter Y in FIG. 6 depicts the zone wherein inherent dampening is provided by the system so as to limit, the maximum amplitude of the vibratory excursions.

In FIGS. 2-3 form of invention, the initial free resilient movement of the cutting blade assembly 24a is provided by virtue of the torsion bar 38 suspension which produces a limited, by resiliently restrained twisting movement thereby imparting the predetermined initial range of movement X to the cutting blade 34 through the curvilinear arms 36 which are attached at opposite ends of the torsion bar 38. Vibratory excursions of the cutting blade assembly 24a imparted by the exciting source or device 52, are limited by the combination of the torsion bar suspension and the absorption of energy through the compression of the opposed springs 40, 42. This limit in the vibratory excursions of the cutting blade assembly 24a is applied to the system only at a point beyond the initial movement (useful working range) X as indicated by the letter Y in FIG. 6 on each side of the cutting blade 34 to obtain maximum force reinforcement in the system without creating an infinite force buildup.

Thus, it will be apparent that cutting blade 34 can be provided with a concentrated high level kinetic energy force so that when the leading edge of the cutting blade 34 engages compacted materials or earth, the compacted materials or earth will define a forward reference point in the X or free range of movement of the cutting blade 34, but the cutting blade 34 is capable of still moving through the remaining defined range of movement imposed on the system by the exciting device 52 limited only by the dampening thereof in the zone Y at opposite ends of the cutting blade 34. In this way, earth or compacted materials can be effectively dislodged without total dependence on the tractive effort level of the vehicle.

The unbalanced force applied by the exciting source or device 52 is preferably at or near the natural resonant frequency of the cutting blade assembly 2411. Forced vibration of the cutting blade assembly 24a at other than the resonant frequency is functional and useful as a practical device, but is less efficient from an energy conversion standpoint than resonant systems, and does not employ the principle of reinforcement to maximum benefit.

Also, while the cutting blade assembly 24a is preferably resiliently mounted by the torsion bar 38 suspension system shown, it will be apparent that a limited amount of unrestrained initial relative movement of the cutting blade assembly 24'a exists prior to the imposition of dampening forces by spring compression being applied thereto. Inversion of this system is possible using compression springs for resilient suspension and torsion bar dampenmg.

Considering now the form of invention shown in FIGS. 4-5, it will be seen that the cutting blade assembly 24b differs in that the torsion bar 38b is journaled in the supporting plates 32b generally along the midpoint as well as the outboard edges of the earth loading and moving shell 22b. The inner supporting plates 32b are fixedly mounted to the torsion bar 38b such as by the pins 35 while the outer supporting plates 32b at opposite edges of the earth loading and moving shell 22b receive the opposite ends of the torsion bar in a freely rotatable condition as in the FIGS. 2-3 embodiment. A pair of elongated arms 36b are attached or otherwise fixed to the torsion bar 38b intermediate the outer supporting plates 32b. Each of the rigid arms 36b are joined to the cutting blade 34b through a pin and clevis connection 52, 54 at the lower end thereof. This linkage configuration also has associated therewith a spring dampening system, including springs 40b, 421;, similar to the FIGS. 2-3 embodiment, and thus will operate in generally the same fashion as the FIGS. 2-3 embodiment. This particular construction, however, affords a very compact mounting of the cutting blade assembly 24b on the back side of the earth loading and moving shell 22b.

In the embodiment illustrated in FIGS. 7-8, a plurality of cantilevered leaf springs 56 are rigidly mounted to the earth loading and moving Shell 220 generally along the midpoint thereof, and the two longer centrally located leaf springs are pivotally mounted through a pin and clevis connection 58, 60 to mount the cutting blade 340 in a cantilever fashion. Springs 400, 420, similar to the FIGS. 2-3 and 4-5 embodiments are employed with this particular design to also provide dampening after initial relative movement of the cutting blade 34c relative to the earth loading and moving shell 220. The plurality of leaf springs stacks 56 will achieve the same results as the torsion bars of the FIGS. 2-3 and 4-5 embodiment in that it will provide for a limited amount of undampened resilient movement of the cutting blade 34c, together with the absorption of forces by reason of its excitation by the exciting device 52. While the leaf spring stacks 56 are illustrated as being mounted in a. substantially vertical plane of spring deflection, it is equally practical to mount the leaf-spring stacks in a manner which will result in a deflection plane which is parallel or coincident with the cutting blade, and in this respect, the leaf spring stacks 56 would be mounted in a generally horizontal fashion.

The FIGS. 9-10 embodiment illustrates the use of opposed, adjacently positioned helical, coil or spirally wound springs 62, 64 at opposite ends of the cutting blade 34d. Initial relative movement of the cutting blade 34d is provided in this embodiment by the resilient suspension system including the smaller outer helical coil or spirally Wound springs 62. The innermost portions of the inner springs 64 are spaced from the supporting plate 44d to provide the X range of movement of the cutting blade 34d prior to establishing inherent dampening in the system through absorption of forces provided by the inner springs 64.

The embodiment of the present invention shown in FIGS. 1l-12 employs concentrically mounted spirally wound springs 66, 68, the outer springs 66 functioning as the means for controlling the vibrations of or for limiting the amplitude of vibratory excursions of the cutting blade 34e caused by the exciting device 52, while the inner springs 68 provide resilient mounting of the cutting blade 34e in the same manner as previously described.

In both the FIGS. 9-10 and FIGS. 11-12 embodiments, there is no pivotal or cantilever mounting of the cutting blades 34d or 3412 respectively; however, this is not necessary for the operation of the device in the aforementioned manner as will be apparent.

Reference is now made to the embodiment illustrated in FIGS. 13-14 which is generally similar to the FIGS. 9-10 and 11-12 embodiments with the exception being that a double acting fluid motor 70 is mounted to the cutting blade 34;f in opposition to an internally carried spirally wound compression spring 72. In other words, this particular embodiment shows that it is possible to combine fluid and mechanical devices 70 and 72 in controlling the vibrations of the cutting blade 34f and in providing the resilient mounting of the cutting blade 34 It will be noted that a rather large supporting plate 74 is provided to provide the proper support for the combination fluid motor and spring device shown in this embodiment. It will be apparent that double acting opposed fluid motor means at opposite ends of a cutting blade may also be employed if desired.

The device shown in the FIGS. 15-16 embodiment operates in a slightly different manner than those previously described. In particular, a pair of opposed compression springs 78 are mounted at each end of the cutting blade 34g transversely thereof to provide motion of the cutting blade 34g generally at right angles to the path of travel of the vehicle. The opposed compression springs 78 are mounted between suitable supporting plates 80 and 81, the first being fixedly mounted to the cutting blade 34g and the latter to earth moving shell 22g. The exciting device 52g produces or imposes a vibratory eifect in a sideways or transverse direction relative to the movement of the vehicle so that the opposed compression springs 76 control maximum vibrations of the cutting blade 34g within the desired limit.

In the embodiment shown in FIGS. 17-18, a vertically mounted torsion bar 38h is provided in conjunction with right hand and left hand spirally wound torsional springs 82, 84 which are mounted between suitable supporting plates 86 afiixed to the earth loading and moving shell 22h. At the lower end of the torsion bar 38h, a toggle arm and pin connection 88, 90 is provided, the latter element being aflixed to the cutting blade 34h so as to produce a sidewise or circular arc motion shearing action at opposite ends of the cutting blade 34h. Specifically, this sidewise or circular arc motion shearing action is such that opposite ends of the blades may be alternatively or concurrently moved in a back and forward fashion generally in line with the movement of the vehicle rather than the transverse movement which is contemplated by the FIGS. 15-16 embodiment.

A slightly different form of invention is shown in the FIGS. 19-20 embodiment wherein a properly designed confined mass 92 is fixedly or otherwise attached to the earth loading and moving shell 22: as illustrated to provide multi-directional excursions. Displacement of the rubber mass 92 and relaxation thereof as caused by the vibratory effect of the exciting device 521 will cause the rubber mass 92 to return to its initial state, and this has the effect of controlling or limiting the vibratory excursions created by the exciting device 521. The rubber mass 92 provides a self dampening system which does not provide the initial resilient mounting system contemplated in the previous embodiments.

In FIGS. 21-23, the present invention is shown as being adapted to an end loader 94- of conventional design. As illustrated, the end loader bucket 96 mounts the cutting blade 34] for a limited amount of initial relative movement through a pin and slot connection 98, 100 adjacent the lower end thereof so that the cutting blade 34 projects forwardly of the end loader bucket 96. A spring absorption system employing compression or coil springs 40 42 similar to that described in connection with the previous embodiments is mounted to the end loader bucket 96 generally at the midpoint thereof, the central supporting plate 44 of the spring absorption system also being mounted to the curvilinear supporting arm which forms part of the cutting blade 34j. The exciting device 52 produces the vibratory excursions of the cutting blade 34 with the spring absorption system acting to limit the excursions of the cutting blade 34 in a manner similar to that described in connection with certain of the previous embodiments such as, for example, the embodiment shown in FIGS. 11-12. Also, when the end loader bucket 96 is in the dump at discharge position, a self-cleaning of the bucket will result by virtue of the vibrating effect which is established.

From the foregoing, it will now be appreciated that the present invention provides novel apparatus for rapid and eflicient dislodging of earth or compacted materials in a manner not contemplated by prior art devices. The invention has utility for various types of construction equipment including, without limitation, scrapers, motor graters, bulldozers, end loaders, backhoes, rippers, land levelers, scarifiers and plows. Although specific embodiments of the invention have been shown and described, it is with full awareness that many modifications thereof are possible. The invention, therefore, is not to be restricted except so far as is necessitated by the appended claims.

What is claimed is:

1. In an earth moving machine, the combination of an earth moving shell having a cutting blade resiliently mounted thereon and positioned adjacent its lower end, the mounting of said cutting blade permitting said blade to move freely with respect to said shell in at least two opposite directions for a predetermined range of movement, means for vibrating said blade through a frequency range including its resonant frequency, and absorption means positioned at the extremes of the predetermined range of free movement for absorbing vibratory excursions of said blade beyond the predetermined range of free movement, said absorption means being inefiective when said blade is within said predetermined range of free movement. H

2. The combination as defined in claim 1 wherein the cutting blade means is resiliently mounted to said earth moving shell by spring means.

3. The combination as defined in claim 1 wherein said cutting blade means is resiliently mounted to said earth moving shell by fluid motor means.

4. The combination as defined in claim 1 wherein said cutting blade means is resiliently mounted to said earth moving shell by combination fluid motor and spring means.

5. The combination as defined in claim 1 wherein said means for vibrating said cutting blade at its resonant frequency is applied directly to said cutting blade means.

6. The combination as defined in claim 1 wherein said means for absorbing vibratory excursions of said cutting blade means comprises a torsion bar operably associated with said cutting blade means to limit the amplitude of its excursion caused by vibrating said cutting blade means at its resonant frequency.

7. The combination as defined in claim 6 wherein said torsion bar is mounted in a substantially horizontal position relative to said earth moving shell, and at least one pivotally mounted arm depending therefrom which supports the cutting blade means adjacent its lower end in the vicinity of the bottom edge of the earth moving shell.

8. The combination as defined in claim 7 wherein each of the pivotally mounted arms is interconnected to said cutting blade means through a pin and clevis connection.

9. The combination as defined in claim 6 wherein said torsion bar is mounted to said earth moving shell in a plane substantially normal to said cutting blade means, and said resiliently mounted cutting blade means is pivotally mounted to said torsion bar adjacent its lower end whereby vibration of said cutting blade means at its resonant frequency provides oscillation thereof and wherein the amplitude of excursion of said blade means is limited by said torsion bar.

10. The combination as defined in claim 1 wherein said means for absorbing the vibratory excursions of said cutting blade means comprises a plurality of leaf springs which are fixedly mounted at one end of said earth moving shell and at its other end are interconnected to the cutting blade means.

11. The combination as defined in claim 1 wherein the means for absorbing the vibratory excursions of said cutting blade means comprises oppositely disposed fluid motor means which have a confined stroke of operation in a plane which is substantially parallel to said cutting blade means.

12. The combination as defined in claim 1 wherein said means for absorbing the vibratory excursions of said cutting blade means comprises opposed spring means which exert spring rate forces in a plane which is substantially parallel to said cutting blade means.

13. The combination as defined in claim 1 wherein said means for absorbing the vibratory excursions of said cutting blade means comprises combination fluid motor and spring means which are operative in a plane which is substantially parallel to said cutting blade means.

14. The combination as defined in claim 1 wherein said means for absorbing the vibratory excursions of said cutting blade means comprises spring means which is mounted to said cutting "blade means in a manner to produce controlled movement thereof in a plane substantially normal to the direction of movement of the earth moving vehicle.

15. The combination as defined in claim 14 wherein said spring means comprises a pair of oppositely acting compression springs which surround a journal fixedly mounted to said cutting blade means in a plane substantially normal to the plane of movement of said cutting blade means.

References Cited UNITED STATES PATENTS 1,067,375 7/1913 Proctor 37-141 2,443,492 6/ 1948 Austin 37-141 2,619,748 12/1952 McIntosh 37-141 2,792,769 5/ 1957 Harshberger 172-40 2,850,815 9/1958 Edwards 37-141 2,986,294 5/1961 Granryd 37-141 XR 3,145,488 8/1964 French 37-141 3,211,236 10/1965 Patton 172-40 3,226,858 1/1966 Spannhake 17240 XR 3,238,646 3/1966 Oldenburg 37-141 3,272,559 9/1966 Haynes 37-141 XR 3,296,985 1/ 1967 Shelton 172-40 XR 3,328,904 7/1967 Voigt et a1 172-40 XR 3,367,716 2/1968 Bodine 172-40 XR FOREIGN PATENTS 519,046 3/1940 Great Britain.

EDGAR S, BURR, Primary Examiner US. Cl. X.R. 37 11s; 17240 

